The invention relates to an air nozzle for pneumatic false-twist spinning having a yarn channel that is formed of at least two segments that are arranged behind one another in moving direction of the yarn and connect to one another with contact surfaces, and having at least one compressed-air duct leading into the yarn channel.
In the case of air nozzles of this type, it is of considerable importance that the direction and the position of the mouth of the compressed-air duct into the yarn channel is positioned precisely. Even small deviations may result in considerable differences in the false-twisting effect. In the case of a known construction (U.S. Pat. No. 4,480,435), it is therefore provided that the yarn channel consists of two segments that are arranged behind one another. One segment forms a housing into which the smaller segment is inserted that also forms a section of the yarn channel with a smaller diameter. The inserted segment contains several compressed-air ducts that are developed as bores and whereby bores with particularly small diameters are to be made possible. The making of these bores requires considerable expenditures if the required precisions are to be maintained.
An objective of the invention is to provide an air nozzle of the initially mentioned type into which compressed-air ducts can be worked in a simple way with a high precision concerning their direction and the position of their mouth.
This objective is achieved by working a groove into one of the segments for the forming of each compressed-air duct. This groove is open in the direction of the contact surface and is covered by the connecting segment.
In the case of this development, the compressed-air ducts are produced in the form of grooves that can be created in a simple way with high precision, for example, by means of milling. The compressed-air channels will then be completed into a closed duct by means of the other segment only when the air nozzle is assembled. Since before the assembly, these compressed air channels are exposed, they can be examined easily with respect to their precision, and if necessary, can be reworked. During this examination, defective segments can also be sorted out.
In a further development of the invention, it is provided that the contact surfaces, between two segments between which the at least one compressed air duct is formed, are developed as conical surfaces. As a result, in an also uncomplicated way, compressed-air ducts can be produced that have a Predetermined slope with respect to the moving direction of the yarn.
In the case of another development of the invention, it is provided that the contact surfaces between two segments, between which the at least one compressed-air duct is formed, are aligned radially with respect to the moving direction of the yarn.
In a further development of the invention, it is provided that the two segments, between which the at least one compressed-air duct is formed, form sections with different diameters for the yarn channel, in which case, the section that follows in yarn moving direction has a larger diameter. By means of this sudden or step-by-step enlargement of the diameter, despite the arrangement of the compressed-air ducts in a radial plane, a clear flow-off direction for the blown-in compressed air is obtained, because it flows off in the direction of the larger diameter of the yarn channel.
In a further development of the invention, it is provided that the segments in moving direction of the yarn, while supporting one another, are clamped into a housing. As a result, it is possible to exchange the segments in order to create air nozzles with a different effect. The segments must then only have outer contours that match the housing, while their interior development that is decisive for their functioning as an air nozzle, can be adapted to the respective conditions. In this case, it is possible, by means of the selection of corresponding segments, to create so-called intake nozzles that, without generating a twist or at least without generating any significant twist, produce an air flow in the moving direction of the yarn, or air nozzles that cause a very strong false twist.
In the case of an advantageous embodiment of the invention, it is provided that the housing--seen in moving direction of the yarn--in the area of one of its ends, is provided with a support surface for a clamping surface of the first one of the segments, and in the area of the other end, is provided with a receiving device for a clamping insert that, in the direction to the support surface, is connected with the last one of the segments in a form-locking way. Into this housing, segments may be clamped that all have the same outer contour, but that may have very different developments in their interiors.
In a further development of the invention, it is provided that the housing, between the support surface and the receiving device of the clamping insert, forms a toroidal chamber that surrounds the segments at a distance, this toroidal chamber being provided with a connection for a compressed-air supply line. As a result, it is possible to arrange segments within the housing, the compressed-air ducts of which may be located at different points.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.